1. Field of the Invention
The present invention relates to an image processing system, and more particularly to an image processing system capable of image forming operation in response to image signals supplied from an original reading device or the like.
2. Description of the Pior Art
There is already proposed an image process in which an image is formed on a recording material by image signals for example obtained by photoelectrically reading an original document with a reader unit.
Such an imaging process has advantages not achievable in the conventional electrostatic copiers, such as permitting the transmission of the original image to a distant location, the storage of the original image in a digital memory or the editing of the original image, since the image information is processed in the form of digital signals. However such digital copying system, if designed for a high resolving power, cannot easily achieve high-speed copying since a very high transfer rate is required for the digital signals, and will become extremely expensive even if such high speed can be technically combined with the high resolving power.
Also in a digital copier in which an image reader for reading the original image is combined with an electrostatic recording unit or printer utilizing a laser beam and a polygon scanner, the synchronization between the reader and the printer is achieved by sending synchronization signals which are synchronized with the rotation of the polygon scanner in the printer unit and controlling the image reading operation of the reader in response to said signals, thereby minimizing the memory capacity required for synchronization.
Such system is associated with a drawback that the image reading operation of the reader is inevitably affected in the case of an abnormality in the synchronization signals generated by the printer.
In the case of connecting plural printers to a reader unit, the reader is synchronized with a particular printer through the transfer of synchronization signals therebetween, and other printers are rendered simultaneously operable by the addition of synchronization memories for signal synchronization.
Such system is however defective in that the image reading operation of the reader is affected in the case of a failure in said particular printer supplying the synchronization signals to said reader, thus further affecting the image forming operations in the remaining normal printers and eventually leading to the failure of the entire system.
Also in a digital image processing system equipped with a reader for reading an original image to generate digital image signals, such reader may be connected with various apparatus, such as a printer for forming an image from digital image signals, a high-capacity memory for example an optical disk memory, a multi-input multi-output apparatus equipped with plural readers, plural printers and a magnetic disk, or a communication control unit for controlling communication lines such as a local network. In such case the use of an exclusive reader or a separate synchronizing unit has been indispensable because the synchronization signals to be used for deriving the digital image signals from the reader vary from apparatus to apparatus to be connected. Also it has been difficult to supply the image signals simultaneously to plural apparatus.
Though there have been proposed various imaging processes for image formation in response to image signals obtained by photoelectrically reading an original, such processes are mostly based on 1-to-1 combination of an image signal output unit and an image forming unit. Simultaneous plural image formations by image signals supplied from an output unit are theoretically possible, but such object cannot be achieved through mere electrical connections and requires adequate control and display. However such system will still be unsatisfactory for the operator if complicated operations are required.